DNA mode: add the distance computations

modules/flann/include/opencv2/flann.hpp

@@ -95,6 +95,8 @@ using ::cvflann::MaxDistance;
 using ::cvflann::HammingLUT;
 using ::cvflann::Hamming;
 using ::cvflann::Hamming2;
+using ::cvflann::DNAmmingLUT;
+using ::cvflann::DNAmming2;
 using ::cvflann::HistIntersectionDistance;
 using ::cvflann::HellingerDistance;
 using ::cvflann::ChiSquareDistance;
@@ -131,6 +133,14 @@ performed using library calls, if available. Lookup table implementation is used
 cv::flann::Hamming2 - %Hamming distance functor. Population count is
 implemented in 12 arithmetic operations (one of which is multiplication).
 
+cv::flann::DNAmmingLUT -  %Adaptation of the Hamming distance functor to DNA comparison.
+As the four bases A, C, G, T of the DNA (or A, G, C, U for RNA) can be coded on 2 bits,
+it counts the bits pairs differences between two sequences using a lookup table implementation.
+
+cv::flann::DNAmming2 - %Adaptation of the Hamming distance functor to DNA comparison.
+Bases differences count are vectorised thanks to arithmetic operations using standard
+registers (AVX2 and AVX-512 should come in a near future).
+
 cv::flann::HistIntersectionDistance - The histogram
 intersection distance functor.
 

modules/flann/include/opencv2/flann/defines.h

@@ -128,6 +128,7 @@ enum flann_distance_t
     FLANN_DIST_KULLBACK_LEIBLER  = 8,
     FLANN_DIST_KL                = 8,
     FLANN_DIST_HAMMING          = 9,
+    FLANN_DIST_DNAMMING          = 10,
 
     // deprecated constants, should use the FLANN_DIST_* ones instead
     EUCLIDEAN = 1,

modules/flann/include/opencv2/flann/dist.h

@@ -744,6 +744,157 @@ private:
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
+struct DNAmmingLUT
+{
+    typedef False is_kdtree_distance;
+    typedef False is_vector_space_distance;
+
+    typedef unsigned char ElementType;
+    typedef int ResultType;
+    typedef ElementType CentersType;
+
+    /** this will count the bits in a ^ b
+     */
+    template<typename Iterator2>
+    ResultType operator()(const unsigned char* a, const Iterator2 b, size_t size) const
+    {
+        static const uchar popCountTable[] =
+        {
+            0, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4
+        };
+        ResultType result = 0;
+        const unsigned char* b2 = reinterpret_cast<const unsigned char*> (b);
+        for (size_t i = 0; i < size; i++) {
+            result += popCountTable[a[i] ^ b2[i]];
+        }
+        return result;
+    }
+
+
+    ResultType operator()(const unsigned char* a, const ZeroIterator<unsigned char> b, size_t size) const
+    {
+        (void)b;
+        static const uchar popCountTable[] =
+        {
+            0, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4,
+            2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 3, 3, 3, 3, 4, 4, 4, 3, 4, 4, 4, 3, 4, 4, 4
+        };
+        ResultType result = 0;
+        for (size_t i = 0; i < size; i++) {
+            result += popCountTable[a[i]];
+        }
+        return result;
+    }
+};
+
+
+template<typename T>
+struct DNAmming2
+{
+    typedef False is_kdtree_distance;
+    typedef False is_vector_space_distance;
+
+    typedef T ElementType;
+    typedef int ResultType;
+    typedef ElementType CentersType;
+
+    /** This is popcount_3() from:
+     * http://en.wikipedia.org/wiki/Hamming_weight */
+    unsigned int popcnt32(uint32_t n) const
+    {
+        n = ((n >> 1) | n) & 0x55555555;
+        n = (n & 0x33333333) + ((n >> 2) & 0x33333333);
+        return (((n + (n >> 4))& 0x0F0F0F0F)* 0x01010101) >> 24;
+    }
+
+#ifdef FLANN_PLATFORM_64_BIT
+    unsigned int popcnt64(uint64_t n) const
+    {
+        n = ((n >> 1) | n) & 0x5555555555555555;
+        n = (n & 0x3333333333333333) + ((n >> 2) & 0x3333333333333333);
+        return (((n + (n >> 4))& 0x0f0f0f0f0f0f0f0f)* 0x0101010101010101) >> 56;
+    }
+#endif
+
+    template <typename Iterator1, typename Iterator2>
+    ResultType operator()(const Iterator1 a, const Iterator2 b, size_t size, ResultType /*worst_dist*/ = -1) const
+    {
+        CV_DbgAssert(!(size % long_word_size_) && "vectors size must be multiple of long words size (i.e. 8)");
+
+#ifdef FLANN_PLATFORM_64_BIT
+        const uint64_t* pa = reinterpret_cast<const uint64_t*>(a);
+        const uint64_t* pb = reinterpret_cast<const uint64_t*>(b);
+        ResultType result = 0;
+        size /= long_word_size_;
+        for(size_t i = 0; i < size; ++i ) {
+            result += popcnt64(*pa ^ *pb);
+            ++pa;
+            ++pb;
+        }
+#else
+        const uint32_t* pa = reinterpret_cast<const uint32_t*>(a);
+        const uint32_t* pb = reinterpret_cast<const uint32_t*>(b);
+        ResultType result = 0;
+        size /= long_word_size_;
+        for(size_t i = 0; i < size; ++i ) {
+            result += popcnt32(*pa ^ *pb);
+            ++pa;
+            ++pb;
+        }
+#endif
+        return result;
+    }
+
+
+    template <typename Iterator1>
+    ResultType operator()(const Iterator1 a, ZeroIterator<unsigned char> b, size_t size, ResultType /*worst_dist*/ = -1) const
+    {
+        CV_DbgAssert(!(size % long_word_size_) && "vectors size must be multiple of long words size (i.e. 8)");
+
+        (void)b;
+#ifdef FLANN_PLATFORM_64_BIT
+        const uint64_t* pa = reinterpret_cast<const uint64_t*>(a);
+        ResultType result = 0;
+        size /= long_word_size_;
+        for(size_t i = 0; i < size; ++i ) {
+            result += popcnt64(*pa);
+            ++pa;
+        }
+#else
+        const uint32_t* pa = reinterpret_cast<const uint32_t*>(a);
+        ResultType result = 0;
+        size /= long_word_size_;
+        for(size_t i = 0; i < size; ++i ) {
+            result += popcnt32(*pa);
+            ++pa;
+        }
+#endif
+        return result;
+    }
+
+private:
+#ifdef FLANN_PLATFORM_64_BIT
+    static const size_t long_word_size_= sizeof(uint64_t)/sizeof(unsigned char);
+#else
+    static const size_t long_word_size_= sizeof(uint32_t)/sizeof(unsigned char);
+#endif
+};
+
+
+
 template<class T>
 struct HistIntersectionDistance
 {